1. Field of the Invention
The present invention relates to an ultrasonic actuated unit including an ultrasonic transmitting portion which extends along a longitudinal axis and which can transmit an ultrasonic vibration from a proximal direction toward a distal direction, wherein the ultrasonic actuated unit is actuated when the ultrasonic vibration is transmitted. The present invention also relates to an ultrasonic treatment device including the ultrasonic actuated unit.
2. Description of the Related Art
Japanese Patent No. 4249064 has disclosed an ultrasonic actuated unit which is actuated when the ultrasonic vibration is transmitted. This ultrasonic actuated unit includes an ultrasonic transmitting portion which can transmit an ultrasonic vibration from a proximal direction toward a distal direction. The ultrasonic transmitting portion includes a horn member serving as a proximal-side transmitting member to which an ultrasonic vibrator that is an ultrasonic generating portion is attached, and a probe serving as a distal-side transmitting member which is connected to the distal direction side of the horn member. The ultrasonic transmitting portion is inserted through a channel of an endoscope. A distal treatment section is provided in a distal portion of the probe, and when the ultrasonic vibration is transmitted to the distal treatment section, a treatment target such as a living tissue is treated by the use of the ultrasonic vibration. When the ultrasonic vibration is transmitted, the ultrasonic transmitting portion performs a longitudinal vibration having a vibration direction parallel to the longitudinal axis at a predetermined reference frequency.
A vibration absorbing member is disposed on an outer peripheral portion of the probe of the ultrasonic transmitting portion at a node position of the longitudinal vibration. The vibration absorbing member is in abutment with an inner peripheral portion of the channel. Here, in the ultrasonic actuated unit, the shape of the ultrasonic transmitting portion about the longitudinal axis may be partly asymmetric, or the material quality of the ultrasonic transmitting portion may be partly nonuniform. In this case, in addition to the longitudinal vibration, an imprecise vibration having a vibration direction which is not parallel to the longitudinal axis is generated. When the imprecise vibration is generated, the imprecise vibration is absorbed by the vibration absorbing member. Since the vibration absorbing member is located at the node position of the longitudinal vibration, the longitudinal vibration is not absorbed by the vibration absorbing member.